Monodisperse colloidal particles are recognized for their ability to form a variety of crystalline structures that are being considered for a wide range of technologies, including photonics (as photonic crystals or as pigments), catalysis, electrochemical devices (e.g., fuel cells and batteries), biomaterials, and drug delivery vehicles. Various structures have been produced using hard-sphere packing mechanisms, including face-centered cubic and body-centered cubic arrangements.
Binary colloidal crystals (ordered arrays of two particle types) have also been produced, using long-range electrostatic or steric repulsive forces (Velikov, et al., Science 296: 106, 2002), short-range attractive interactions such as DNA bridges (Soto, et al., J. Am. Chem. Soc. 2002(124):8508, 2002), or contact hard-sphere interactions (see Bartlett, et al., Phys. Rev. Lett., 68(25):3801, 1992, and Schofield, Phys. Rev. E 64:051403, 2001). While a wider variety of systems can be achieved using binary particle systems, current methods limit crystal structures to the types found in metallic systems (e.g., the CsCl structure, which is found in the Cu—Zn and Al—Ni alloy systems).